Re: [LKP] [btrfs] 8d47a0d8f7: fio.write_bw_MBps -28.6% regression

[David Sterba]

On Fri, Apr 10, 2020 at 02:44:55PM +0800, Qu Wenruo wrote:
> On 2020/4/10 äå2:34, Xing Zhengjun wrote:
> > Hi Wenruo,
> > 
> > ÂÂ We test it in v5.6, the issue still exist, do you have time to take a
> > look at this? Thanks.
> 
> This is expected.
> 
> The extra check brings new overhead mostly equal to another CRC32 run.
> 
> We believe it's worthy, as our read time tree checker has exposed quite
> some bit flip corruption.

The test probably runs on a PMEM device so there's no slowdown from the
actual IO and the in-memory checks are measurable, though 28% is a lot,
I'd expect something like 5-10% at most.